Thermona THERM 18 KD Owner's manual

Manual for installation,
operation and maintenance
of boiler
Hanging gas condensing boiler
THERM 18 KD, KDZ, KDC, KDZ 5
THERM 25 KD, KDZ, KDC, KDZ 5
THERM 35 KD, KDZ, KDC, KDZ 5

Manual for installation,
service and maintenance
of boiler
THERM 18 KD, KDZ, KDC, KDZ 5
THERM 25 KD, KDZ, KDC, KDZ 5
THERM 35 KD, KDZ, KDC, KDZ 5

CONTENTS
1. General information ..................................................................................4
1.1 Use ........................................................................................................4
1.2 Equipment details .........................................................................................4
1.2.1 Equipment description..............................................................................4
1.2.2 Construction variants ...............................................................................4
1.2.3 General description .................................................................................5
1.2.4 Simplied hydraulic and functional diagrams (are not source materials for assembly) .................5
1.3 Operational safety .........................................................................................7
1.4 Technical parameters ......................................................................................8
1.5 Set of boilers..............................................................................................14
2. User manual .........................................................................................16
2.1 Control and signalling.....................................................................................16
2.1.1 Boiler control panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
2.1.2 LCD display ........................................................................................17
2.1.3 Custom menu .....................................................................................18
2.1.4 Error messages ....................................................................................20
2.2 Activation and deactivation of the boiler...................................................................21
2.2.1 Commissioning of the boiler .......................................................................21
2.2.2 Disconnection of the boiler from operation .........................................................21
2.3 Regulation................................................................................................22
2.3.1 Operation of the boiler without the room thermostat or regulator ...................................22
2.3.2 Operation of the boiler with spatial thermostat .....................................................22
2.3.3 Operation of the boiler using built-in equithermal regulation........................................23
2.3.4 Operation of the boiler using built-in equithermal regulation........................................25
2.3.5 Heating of utility water (DHW) .....................................................................25
2.3.5.1 Flow heating DHW – (KDC boiler)..........................................................25
2.3.5.2 Storage water heating (KDZ boilers – with athermostat-equipped storage tank) ............25
2.3.5.3 Storage water heating (KDZ 5 and KDZ boilers with astorage tank with an NTC
temperature sensor)......................................................................25
2.3.6 The heating of water in the accumulator storage tank is in the connection with solar panels..........26
2.4 Selected protective functions of the boiler .................................................................27
2.5 Maintenance and service..................................................................................28
2.5.1 Additionally lling the heating system..............................................................28
2.6 Warranty and warranty terms..............................................................................28
3. Installation manual ..................................................................................29
3.1 Basic instructions for assembly of the boiler................................................................29
3.2 Complete character of the delivery ........................................................................29
3.3 Location of the boiler .....................................................................................30
3.4 Suspending the boiler.....................................................................................31
3.5 Connecting the boiler to the hot-water system.............................................................31
3.5.1 Dimensions and connection........................................................................32
3.5.2 Graphs of the connecting overpressures of heating water (on the output for heating water)..........33
3.5.3 Expansion tank ....................................................................................34
3.5.4 Using anti-freeze mixtures .........................................................................34
3.5.5 Safety valve........................................................................................34
3.6 Connection of boiler THERM 18, 25, 35 KDZ 5 and 18, 25, 35 KDC to the distribution of service water.........34
3.7 Connection of the boiler to the gas distribution ............................................................35
3.7.1 Conversion to other fuels...........................................................................35
3.8 Filling and discharging of the heating system ..............................................................35
3.8.1 Procedure for lling the heating system ............................................................35
3.8.2 Additional lling of water into the heating system ..................................................35
3.8.3 Discharging of water from the heating system ......................................................35
3.9 Condensate outlet ........................................................................................36
3.10 Design of gas exhaust.....................................................................................36
3.11 Connection of the boiler to the storage tank ...............................................................38
3.12 Connection of the boiler to the electricity network .........................................................38
3.12.1 Connection of the room thermostat ................................................................38
3.12.2 Connection of aroom regulator with OpenTherm+ communication .................................38
3.13 Variants for the installation of the boiler ...................................................................39
4. Additional information for service ....................................................................40
4.1 Gas fitting B&P SGV - setting ..............................................................................40
4.2 Adjusting boiler combustion (calibration)..................................................................40
4.3 Electrical connection diagram .............................................................................43
5. Record of warranty and post-warranty repairs and annual controls......................................46
6. Production information sheets........................................................................47
7. Certicate of quality and completeness of the product .................................................59
!
Grac symbols
used in the text:
Notication of the producer directly related to the
operational safety of the consumer appliance
Information recommended
by the producer

4THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
1.1 Use
The hanging condensing boilers THERM are modern gas hot water boilers that burn natural gas. The boilers are constructed as
consumer appliances using condensed water steam in the combustion process with excellent eciency, minimum emissions
into the air and the minimum consumption of electricity. Operation is economical and does not strain so the environment.
The output of the boiler can be uently regulated within the scope of 10 – 100 % and adapted automatically to immediate
thermal losses from the object.
Versions of THERM condensing boilers can be used, in addition to heating, to prepare hot water (hereinafter referred to as
DHW) in an indirect storage tank, external or built-in, or using aow method.
!The boiler is designed for closed heating systems tted with an expansion vessel or open expansion vessel
aminimum height of 8m above the boiler.
1.2 Equipment details
1.2.1 Equipment description
this concerns the hanging condensing boiler designed for heating building with athermal loss of up to 37 kW
option for heating DHW – ow heating or heating in an indirect heating storage tank
natural gas operation or propan
fully automated operation
low consumption of electricity
automatic continuous output modulation in the ratio of up to 1:10
simple boiler control
high comfort level
built-in equithermal regulation
ability to control by the superior indoor thermostat or intelligent indoor control unit
high level of operational safety
security elements of the boiler prevent overheating of the boiler or the escape of the eects of burnt gases
built-in energy-saving circulating pump with electronic speed modulation
safety valve 3 bar
protective functions (anti-freeze protection, pump protection, etc.)
electric ignition (saving of fuel)
built-in automatic by-pass
1.2.2 Construction variants
THERM 18 KD, 25 KD, 35 KD
closed combustion chamber – TURBO variant
variant designed only for heating
air for combustion is sucked in from the open air
THERM 18 KDZ, 25 KDZ, 35 KDZ
closed combustion chamber – TURBO variant
heating of water in indirect heating external storage tank
air for combustion is sucked in from the open air
THERM 18 KDC, 25 KDC, 35 KDC
closed combustion chamber – TURBO variant
heating of DHW using aow method
air for combustion is sucked in from the open air
THERM 18 KDZ 5, 25 KDZ 5, 35 KDZ 5
closed combustion chamber – TURBO variant
heating of water in the stainless indirect built-in storage tank with the volume 55l
air for combustion is sucked in from the open air
1. GENERAL INFORMATION

5
THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
1.2.3 General description
The basis element of THERM gas condensing boilers is the load-bearing frame in which individual elements are mounted.
In the upper part of the boiler is acondensing body, which associates the combustion chamber with the burner and the
two-chamber stainless exchanger. The coating of the condensing boiler consists of an external thermo-plastic shell, which is
reinforced by an internal stainless wall which signicantly restricts the passage of heat into the surroundings. The heat transfer
surfaces of the exchangers consist of round tubes which must be protected against blocking by dirt from the heating system.
Therefore, it is required to install alter with asludge trap on the return water inlet line. The collector on the output for the
heating water from the body is tted with ade-aerating valve. The removable front burner face of the element is equipped
with amultifunctional electrode, aBLUEJET ash pipe, and shaped pipeline for the inlet of the gas and air mixture.
The suitable mix of fuel for burning is prepared by mutual action of the multiphase fan, mixer, electrically modulated gas
valve and controlling automatics of the boiler. Together, these components create acompact and active control system
of the combustion process. Using acompound electrode of the burner wall of the condensation body, the electronics
receives feedback information about the status of burning and optimizes the program map so that the combustion process
is continuously optimal.
Condensate is created during the operation of the condensation boiler. The outow of condensate from the condensation
body, exhaust piping for burnt gases and the supply of air are directed by hoses into the odour closure if the condensate ows
outside the boiler. To ensure the ow of water through the boiler, the return water inlet is equipped with aWilo energy-saving
pump with electronically controlled speed. The circulating pump is integrated in acompact hydro-block, which also includes
abypass, avalve for lling up the heating system, apressure sensor, asafety valve, the connection to the expansion vessel etc.
The THERM 18 KDZ, 25 KDZ and 35 KDZ boilers are equipped with athree-way valve for the distribution of the hot water heating
function and heating system function. Moreover, the 18 KDC, 25 KDC, 35 KDC version also includes aplate heat exchanger
that provides comfort heating of water.
On the front side of the boiler there are control elements and display (see “User Manual“ chapter). The control panel includes
control microprocessor automatics for controlling the activities of the boiler, combustion, boiler safety and regulation.
1.2.4 Simplied hydraulic and functional diagrams (are not source materials for assembly)
THERM 18 KD, 25 KD, 35 KD
1 - Gas valve
2 - Safety valve
3 - Circulation pump
4 - Expansion heating vessel
5 - Ventilator
6 - Emergency thermostat
7 - Thermal probe
8 - Flue gas temperature probe
9 - Mixer
10 - Gulley trap (siphon)
11 - Hydroblock
12 - Condensing body
A- Input for gas
B - Input for returned water
C - Output for heating water
C BA
12
11
10
9
8
7
65
4
3
2
1

6THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
THERM 18 KDZ, 25 KDZ, 35 KDZ
1 - Gas valve
2 - Safety valve
3 - Circulation pump
4 - Expansion heating vessel
5 - Ventilator
6 - Emergency thermostat
7 - Thermal probe
8 - Flue gas temperature probe
9 - Mixer
10 - Gulley trap (siphon)
11 - Hydroblock
12 - Condensing body
13 - Three-way valve
A- Input for gas
B - Input for returned water
C - Output for heating water
D - Input for heating water from tank
E - Output for heating water into tank
THERM 18 KDC, 25 KDC, 35 KDC
1 - Plate exchanger
2 - Safety valve
3 - Circulation pump
4 - Expansion heating vessel
5 - Ventilator
6 - Emergency thermostat
7 - Thermal probe
8 - Flue gas temperature probe
9 - Mixer
10 - Gulley trap (siphon)
11 - Flow switch for heating DHW
12 - Condensing body
13 - Three-way valve
14 - Hydroblock
15 - Gas valve
A- Input for gas
B - Input for returned water
C - Output for heating water
D - Input for utility water
E - Output for utility water
C BAE D
13
12
11
10
9
8
7
65
4
3
2
1
C BAE D
14
13
12
11
10
9
8
7
65
4
3
2
1
15

7
THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
In the case of gas odour:
close the gas valve under the boiler
ensure ventilation of the room (windows, door)
donot manipulate the electric switch
liquidate any naked ame
immediately call service (the boiler must not be used until after the service inspection)
In the case of an odour of combustion burnt gases:
disconnect the boiler
ensure ventilation of the room (windows, door)
call service (the boiler must not be used until after the service inspection)
In the case of aconsumer appliance re:
close the gas valve under the consumer appliance
disconnect the consumer appliance from the electricity network
liquidate the re with powder extinguishing equipment or afoam extinguisher
!THERM boilers are tted with all safety, emergency and protective elements to ensure completely safe boiler
operation. If irrespective of this, e.g. due to unprofessional intervention, irregular inspections and revisions of
the boiler, etc., there is anon-standard status then we recommend proceeding as follows:
1.3 Operational safety
THERM 18 KDZ 5, 25 KDZ 5, 35 KDZ 5
1 - Gas valve
2 - Safety valve
3 - Circulation pump
4 - Expansion heating vessel
5 - Ventilator
6 - Emergency thermostat
7 - Thermal probe
8 - Flue gas temperature probe
9 - Mixer
10 - Gulley trap (siphon)
11 - Hydroblock
12 - Condensing body
13 - Three-way valve
14 - Tank DHW
15 - Expansion tank DHW
A- Input for gas
B - Input for returned water
C - Output for heating water
D - Output for utility water from tank
E - Input for utility water into tank
F - Hot water circulation inlet
12
11
10
9
8
7
6
5
4
32
1
C BA EDF
13 14
15

8THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
1.4 Technical parameters
Technical description Unit THERM 18 KD THERM 18 KDC
Fuel -natural gas propane natural gas propane
Consumer appliance category - I2H , II2H3P I3P , II2H3P I2H , II2H3P I3P , II2H3P
Construction - C13, C33, C43, C53, C83, C93
Nominal thermal input for heating QnkW 18,0 18,0 18,0 18,0
Minimal thermal input for heating QnkW 1,8 1,8 1,8 1,8
Nominal thermal output
for heating Pn
Δt = 80/60 °C kW 17, 5 17,5 17, 5 17,5
Δt = 50/30 °C kW 19,0 19,0 19,0 19,0
Nominal thermal input for heating of DHW
Qnw
kW - - 24,0 24,0
Nominal thermal output for heating DHW kW - - 23,5 23,5
Minimal thermal output
Pn
Δt = 50/30 °C kW 1,8 1,8 1,8 1,8
Δt = 80/60 °C kW 1,7 1,7 1,7 1,7
Drilling gas curtains mm 4,3 4,3 5,3 5,3
Gas overpressure on the consumer appliance
input mbar 20 37 (50) 20 37 (50)
Consumption of gas m3.h-1 0,181 – 1,749 0,070 – 0,711 0,181 – 2,500 0,070 – 0,920
Maximum overpressure of heating
system PMS bar 3333
Minimum overpressure of heating system bar 0,8 0,8 0,8 0,8
Max. input pressure DHW PMW bar - - 6 6
Min. input pressure DHW bar - - 0,5 0,5
Maximum input pressure of cold water °C 80 80 80 80
Flue-gas installation alternatives mm 60/100, 80/125, 2x 80 60/100, 80/125, 2x 80
Average temperature of burnt gases °C 50 50 50 50
Flue gas temperature in case of overheating °C 84 84 85 85
Lowest ue gas temperature at min. heating
output °C 32 32 32 32
Weight ow of burnt gases g.s-1 1,0 – 8,6 1,0 – 8,6 1,0 – 10,2 1,0 – 10,2
Acoustic performance level dB (A) 54 54 54 54
Boiler eciency % 98 – 106 98 – 106 98 – 106 98 – 106
NOx class of boiler - 6 6 6 6
Type of electricity supply - ~ ~ ~ ~
Nominal supply voltage / frequency V/ Hz 230 / 50 230 / 50 230 / 50 230 / 50
Auxiliary
electricity at
nominal heat input power W 68,2 68,2 68,2 68,2
partial loading W21,4 21,4 21,4 21,4
emergency status W4,1 4,1 4,1 4,1
Nominal current of the circuit breaker for
consumer appliance A2222
Level of coverage of electrical part - IP 41 (D) IP 41 (D) IP 41 (D) IP 41 (D)
Environment according to ČSN 332000 – 3 - basic AA5 / AB5 basic AA5 / AB5
Volume of expansion unit l 7 7 7 7
Filling overpressure of expansion vessels bar 1111
Flow of DHW at ∆t = 30 °C l.min-1 - - 11,0 11,0
Dimensions of boiler: height / width / depth mm 725 / 430 / 280 725 / 430 / 280
Weight of boiler kg 28 28 29 29

9
THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
Technical description Unit THERM 18 KDZ THERM 18 KDZ 5
Fuel -natural gas propane natural gas propane
Consumer appliance category - I2H , II2H3P I3P , II2H3P I2H , II2H3P I3P , II2H3P
Construction - C13, C33, C43, C53, C83, C93
Nominal thermal input for heating QnkW 18,0 18,0 18,0 18,0
Minimal thermal input for heating QnkW 1,8 1,8 1,8 1,8
Nominal thermal output
for heating Pn
Δt = 80/60 °C kW 17, 5 17,5 17, 5 17,5
Δt = 50/30 °C kW 19,0 19,0 19,0 19,0
Nominal thermal input for heating of DHW
Qnw
kW 18,0 18,0 18,0 18,0
Nominal thermal output for heating DHW kW 17, 5 17,5 17, 5 17,5
Minimal thermal output
Pn
Δt = 50/30 °C kW 1,8 1,8 1,8 1,8
Δt = 80/60 °C kW 1,7 1,7 1,7 1,7
Drilling gas curtains mm 4,3 4,3 4,3 4,3
Gas overpressure on the consumer appliance
input mbar 20 37 (50) 20 37 (50)
Consumption of gas m3.h-1 0,181 – 1,749 0,070 – 0,711 0,181 – 1,749 0,070 – 0,711
Maximum overpressure of heating
system PMS bar 3333
Minimum overpressure of heating system bar 0,8 0,8 0,8 0,8
Max. input pressure DHW PMW bar - - 6 6
Min. input pressure DHW bar - - 0,5 0,5
Maximum input pressure of cold water °C 80 80 80 80
Flue-gas installation alternatives mm 60/100, 80/125, 2x 80 60/100, 80/125, 2x 80
Average temperature of burnt gases °C 50 50 50 50
Flue gas temperature in case of overheating °C 84 84 84 84
Lowest ue gas temperature at min. heating
output °C 32 32 32 32
Weight ow of burnt gases g.s-1 1,0 – 8,6 1,0 – 8,6 1,0 – 8,6 1,0 – 8,6
Acoustic performance level dB (A) 54 54 54 54
Boiler eciency % 98 – 106 98 – 106 98 – 106 98 – 106
NOx class of boiler - 6 6 6 6
Type of electricity supply - ~ ~ ~ ~
Nominal supply voltage / frequency V/ Hz 230 / 50 230 / 50 230 / 50 230 / 50
Auxiliary
electricity at
nominal heat input power W 68,2 68,2 68,2 68,2
partial loading W21,4 21,4 21,4 21,4
emergency status W4,1 4,1 4,1 4,1
Nominal current of the circuit breaker for
consumer appliance A2222
Level of coverage of electrical part - IP 41 (D) IP 41 (D) IP 41 (D) IP 41 (D)
Environment according to ČSN 332000 – 3 - basic AA5 / AB5 basic AA5 / AB5
Volume of expansion unit l 7 7 7 7
Filling overpressure of expansion vessels bar 1111
Volume of built-in storage tank for water l - - 55 55
Maintained temperature of hot water in the
storage tank °C - - 65 65
Volume of expansion unit of DHW l - - 2 2
Dimensions of boiler: height / width / depth mm 725 / 430 / 280 725 / 800 / 385
Weight of boiler kg 29 29 54 54

10 THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
Technical description Unit THERM 25 KD THERM 25 KDC
Fuel -natural gas propane natural gas propane
Consumer appliance category - I2H , II2H3P I3P , II2H3P I2H , II2H3P I3P , II2H3P
Construction - C13, C33, C43, C53, C83, C93
Nominal thermal input for heating QnkW 23,5 23,5 23,5 23,5
Minimal thermal input for heating QnkW 2,5 2,5 2,5 2,5
Nominal thermal output
for heating Pn
Δt = 80/60 °C kW 22,9 22,8 22,9 22,8
Δt = 50/30 °C kW 24,9 24,6 24,9 24,6
Nominal thermal input for heating of DHW
Qnw
kW - - 23,5 23,5
Nominal thermal output for heating DHW kW - - 23,0 23,0
Minimal thermal output
Pn
Δt = 50/30 °C kW 2,65 2,65 2,65 2,65
Δt = 80/60 °C kW 2,45 2,45 2,45 2,45
Drilling gas curtains mm 5,6 5,6 5,6 5,6
Gas overpressure on the consumer appliance
input mbar 20 37 (50) 20 37 (50)
Consumption of gas m3.h-1 0,26 – 2,50 0,10 – 0,92 0,26 – 2,50 0,10 – 0,92
Maximum overpressure of heating
system PMS bar 3333
Minimum overpressure of heating system bar 0,8 0,8 0,8 0,8
Max. input pressure DHW PMW bar - - 6 6
Min. input pressure DHW bar - - 0,5 0,5
Maximum input pressure of cold water °C 80 80 80 80
Flue-gas installation alternatives mm 60/100, 80/125, 2x 80 60/100, 80/125, 2x 80
Average temperature of burnt gases °C 50 50 50 50
Flue gas temperature in case of overheating °C 85 85 85 85
Lowest ue gas temperature at min. heating
output °C 32 32 32 32
Weight ow of burnt gases g.s-1 1,6 – 10,2 1,6 – 10,2 1,6 – 10,2 1,6 – 10,2
Acoustic performance level dB (A) 54 54 54 54
Boiler eciency % 98 – 106 98 – 106 98 – 106 98 – 106
NOx class of boiler - 6 6 6 6
Type of electricity supply - ~ ~ ~ ~
Nominal supply voltage / frequency V/ Hz 230 / 50 230 / 50 230 / 50 230 / 50
Auxiliary
electricity at
nominal heat input power W 68,2 68,2 68,2 68,2
partial loading W21,4 21,4 21,4 21,4
emergency status W4,1 4,1 4,1 4,1
Nominal current of the circuit breaker for
consumer appliance A2222
Level of coverage of electrical part - IP 41 (D) IP 41 (D) IP 41 (D) IP 41 (D)
Environment according to ČSN 332000 – 3 - basic AA5 / AB5 basic AA5 / AB5
Volume of expansion unit l 7 7 7 7
Filling overpressure of expansion vessels bar 1111
Flow of DHW at ∆t = 30 °C l.min-1 - - 11,0 11,0
Dimensions of boiler: height / width / depth mm 725 / 430 / 280 725 / 430 / 280
Weight of boiler kg 28 28 29 29

11
THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
Technical description Unit THERM 25 KDZ THERM 25 KDZ 5
Fuel -natural gas propane natural gas propane
Consumer appliance category - I2H , II2H3P I3P , II2H3P I2H , II2H3P I3P , II2H3P
Construction - C13, C33, C43, C53, C83, C93
Nominal thermal input for heating QnkW 23,5 23,5 23,5 23,5
Minimal thermal input for heating QnkW 2,5 2,5 2,5 2,5
Nominal thermal output
for heating Pn
Δt = 80/60 °C kW 22,9 22,8 22,9 22,8
Δt = 50/30 °C kW 24,9 24,6 24,9 24,6
Nominal thermal input for heating of DHW
Qnw
kW 23,5 23,5 23,5 23,5
Nominal thermal output for heating DHW kW 23,0 23,0 23,0 23,0
Minimal thermal output
Pn
Δt = 50/30 °C kW 2,65 2,65 2,65 2,65
Δt = 80/60 °C kW 2,45 2,45 2,45 2,45
Drilling gas curtains mm 5,6 5,6 5,6 5,6
Gas overpressure on the consumer appliance
input mbar 20 37 (50) 20 37 (50)
Consumption of gas m3.h-1 0,26 – 2,50 0,10 – 0,92 0,26 – 2,50 0,10 – 0,92
Maximum overpressure of heating
system PMS bar 3333
Minimum overpressure of heating system bar 0,8 0,8 0,8 0,8
Max. input pressure DHW PMW bar - - 6 6
Min. input pressure DHW bar - - 0,5 0,5
Maximum input pressure of cold water °C 80 80 80 80
Flue-gas installation alternatives mm 60/100, 80/125, 2x 80 60/100, 80/125, 2x 80
Average temperature of burnt gases °C 50 50 50 50
Flue gas temperature in case of overheating °C 85 85 85 85
Lowest ue gas temperature at min. heating
output °C 32 32 32 32
Weight ow of burnt gases g.s-1 1,6 – 10,2 1,6 – 10,2 1,6 – 10,2 1,6 – 10,2
Acoustic performance level dB (A) 54 54 54 54
Boiler eciency % 98 – 106 98 – 106 98 – 106 98 – 106
NOx class of boiler - 6 6 6 6
Type of electricity supply - ~ ~ ~ ~
Nominal supply voltage / frequency V/ Hz 230 / 50 230 / 50 230 / 50 230 / 50
Auxiliary
electricity at
nominal heat input power W 68,2 68,2 68,2 68,2
partial loading W21,4 21,4 21,4 21,4
emergency status W4,1 4,1 4,1 4,1
Nominal current of the circuit breaker for
consumer appliance A2222
Level of coverage of electrical part - IP 41 (D) IP 41 (D) IP 41 (D) IP 41 (D)
Environment according to ČSN 332000 – 3 - basic AA5 / AB5 basic AA5 / AB5
Volume of expansion unit l 7 7 7 7
Filling overpressure of expansion vessels bar 1111
Volume of built-in storage tank for water l - - 55 55
Maintained temperature of hot water in the
storage tank °C - - 65 65
Volume of expansion unit of DHW l - - 2 2
Dimensions of boiler: height / width / depth mm 725 / 430 / 280 725 / 800 / 385
Weight of boiler kg 29 29 54 54

12 THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
Technical description Unit THERM 35 KD THERM 35 KDC
Fuel -natural gas propane natural gas propane
Consumer appliance category - I2H , II2H3P I3P , II2H3P I2H , II2H3P I3P , II2H3P
Construction - C13, C33, C43, C53, C83, C93
Nominal thermal input for heating QnkW 35,0 35,0 35,0 35,0
Minimal thermal input for heating QnkW 3,5 3,5 3,5 3,5
Nominal thermal output
for heating Pn
Δt = 80/60 °C kW 34,0 34,0 34,0 34,0
Δt = 50/30 °C kW 37,0 37,0 37,0 37,0
Nominal thermal input for heating of DHW
Qnw
kW - - 35,0 35,0
Nominal thermal output for heating DHW kW - - 34,0 34,0
Minimal thermal output
Pn
Δt = 50/30 °C kW 3,4 3,6 3,4 3,6
Δt = 80/60 °C kW 3,2 3,3 3,2 3,3
Drilling gas curtains mm 6,0 6,0 6,0 6,0
Gas overpressure on the consumer appliance
input mbar 20 37 (50) 20 37 (50)
Consumption of gas m3.h-1 0,33 – 3,50 0,14 – 1,45 0,33 – 3,50 0,14 – 1,45
Maximum overpressure of heating
system PMS bar 3333
Minimum overpressure of heating system bar 0,8 0,8 0,8 0,8
Max. input pressure DHW PMW bar - - 6 6
Min. input pressure DHW bar - - 0,5 0,5
Maximum input pressure of cold water °C 80 80 80 80
Flue-gas installation alternatives mm 60/100, 80/125, 2x 80 60/100, 80/125, 2x 80
Average temperature of burnt gases °C 58 58 58 58
Flue gas temperature in case of overheating °C 88 88 88 88
Lowest ue gas temperature at min. heating
output °C 38 38 38 38
Weight ow of burnt gases g.s-1 1,0 – 15,0 1,0 – 15,0 1,0 – 15,0 1,0 – 15,0
Acoustic performance level dB (A) 54 54 54 54
Boiler eciency % 97 – 106 97 – 106 97 – 106 97 – 106
NOx class of boiler - 6 6 6 6
Type of electricity supply - ~ ~ ~ ~
Nominal supply voltage / frequency V/ Hz 230 / 50 230 / 50 230 / 50 230 / 50
Auxiliary
electricity at
nominal heat input power W 68,2 68,2 68,2 68,2
partial loading W21,4 21,4 21,4 21,4
emergency status W4,1 4,1 4,1 4,1
Nominal current of the circuit breaker for
consumer appliance A2222
Level of coverage of electrical part - IP 41 (D) IP 41 (D) IP 41 (D) IP 41 (D)
Environment according to ČSN 332000 – 3 - basic AA5 / AB5 basic AA5 / AB5
Volume of expansion unit l 7 7 7 7
Filling overpressure of expansion vessels bar 1111
Flow of DHW at ∆t = 30 °C l.min-1 - - 16,0 16,0
Dimensions of boiler: height / width / depth mm 725 / 430 / 300 725 / 430 / 300
Weight of boiler kg 28 28 29 29

13
THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
Technical description Unit THERM 35 KDZ THERM 35 KDZ 5
Fuel -natural gas propane natural gas propane
Consumer appliance category - I2H , II2H3P I3P , II2H3P I2H , II2H3P I3P , II2H3P
Construction - C13, C33, C43, C53, C83, C93
Nominal thermal input for heating QnkW 35,0 35,0 35,0 35,0
Minimal thermal input for heating QnkW 3,5 3,5 3,5 3,5
Nominal thermal output
for heating Pn
Δt = 80/60 °C kW 34,0 34,0 34,0 34,0
Δt = 50/30 °C kW 37,0 37,0 37,0 37,0
Nominal thermal input for heating of DHW
Qnw
kW 23,5 23,5 23,5 23,5
Nominal thermal output for heating DHW kW 34,0 34,0 34,0 34,0
Minimal thermal output
Pn
Δt = 50/30 °C kW 3,4 3,6 3,4 3,6
Δt = 80/60 °C kW 3,2 3,3 3,2 3,3
Drilling gas curtains mm 6,0 6,0 6,0 6,0
Gas overpressure on the consumer appliance
input mbar 20 37 (50) 20 37 (50)
Consumption of gas m3.h-1 0,33 – 3,50 0,14 – 1,45 0,33 – 3,50 0,14 – 1,45
Maximum overpressure of heating
system PMS bar 3333
Minimum overpressure of heating system bar 0,8 0,8 0,8 0,8
Max. input pressure DHW PMW bar - - 6 6
Min. input pressure DHW bar - - 0,5 0,5
Maximum input pressure of cold water °C 80 80 80 80
Flue-gas installation alternatives mm 60/100, 80/125, 2x 80 60/100, 80/125, 2x 80
Average temperature of burnt gases °C 58 58 58 58
Flue gas temperature in case of overheating °C 88 88 88 88
Lowest ue gas temperature at min. heating
output °C 38 38 38 38
Weight ow of burnt gases g.s-1 1,0 – 15,0 1,0 – 15,0 1,0 – 15,0 1,0 – 15,0
Acoustic performance level dB (A) 54 54 54 54
Boiler eciency % 97 – 106 97 – 106 97 – 106 97 – 106
NOx class of boiler - 6 6 6 6
Type of electricity supply - ~ ~ ~ ~
Nominal supply voltage / frequency V/ Hz 230 / 50 230 / 50 230 / 50 230 / 50
Auxiliary
electricity at
nominal heat input power W 68,2 68,2 68,2 68,2
partial loading W21,4 21,4 21,4 21,4
emergency status W4,1 4,1 4,1 4,1
Nominal current of the circuit breaker for
consumer appliance A2222
Level of coverage of electrical part - IP 41 (D) IP 41 (D) IP 41 (D) IP 41 (D)
Environment according to ČSN 332000 – 3 - basic AA5 / AB5 basic AA5 / AB5
Volume of expansion unit l 7 7 7 7
Filling overpressure of expansion vessels bar 1111
Volume of built-in storage tank for water l - - 55 55
Maintained temperature of hot water in the
storage tank °C - - 65 65
Volume of expansion unit of DHW l - - 2 2
Dimensions of boiler: height / width / depth mm 725 / 430 / 280 725 / 800 / 385
Weight of boiler kg 29 29 54 54

14 THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
1.5 Set of boilers
THERM 18 KD, 25 KD, 35 KD
1 - Condensing chamber
2 - Ventilator
3 - Heating temperature probe
4 - Expansion heating vessel
5 - Emergency thermostat
6 - Energy saving pump
7 - Gas valve
8 - Safety valve
9 - Control panel
10 - Compound ignition and ionising electrode
5
3
8
6
9
1
4
2
7
THERM 18 KDZ, 25 KDZ, 35 KDZ
1 - Condensing chamber
2 - Ventilator
3 - Heating temperature probe
4 - Expansion heating vessel
5 - Emergency thermostat
6 - Energy saving pump
7 - Gas valve
8 - Safety valve
9 - Control panel
10 - Compound ignition and ionising electrode
11 - Three-way valve
5
3
8
6
9
14
2
7
10
10
11

15
THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
1 - Condensing chamber
2 - Ventilator
3 - Heating temperature probe
4 - Expansion heating vessel
5 - Emergency thermostat
6 - Energy saving pump
7 - Gas valve
8 - Tank DHW
9 - Control panel
10 - Compound ignition and ionising
electrode
11 - Three-way valve
12 - Expansion tank DHW
5
3
8
6
9
1
4
2
7
10
THERM 18 KDZ 5, 25 KDZ 5, 35 KDZ 5
THERM 18 KDC, 25 KDC, 35 KDC
1 - Condensing chamber
2 - Ventilator
3 - Heating temperature probe
4 - Expansion heating vessel
5 - Emergency thermostat
6 - Energy saving pump
7 - Gas valve
8 - Safety valve
9 - Control panel
10 - Compound ignition and ionising electrode
11 - Three-way valve
12 - Plate exchanger
5
3
8
6
9
1
4
2
7
10
11
12
11
12

16 THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
2.1 Control and signalling
2. USER MANUAL
temperature of
heating water
(shift of equithermal curve) DHW temperature
display
disconnection of
water heating
Controls function
Switching boiler on / off – when off, the protective functions of the boiler remain active (when the boiler is
connected to the power supply and the gas inlet is open). If selecting this mode, the boiler display only indicates
the pressure in the heating system, the heating is disconnected, there is heating of TUV and, at the same time, the
backlit display is --. After activation, the boiler display shows information about the type of the burned gas (N – natural
gas, L – LPG) and output (type) of the boiler in kW. Then, the display is tested; all the available symbols are displayed.
After the test, it is possible to choose the winter or summer mode of the boiler.
Reset – unblocking the failure status of the boiler
Winter / summer regime
Winter regime (heating and heating of DHW is ON)
Summer regime (only heating of DHW is ON, the heating is OFF)
Comfort function activation / deactivation – it is used for amore exible start of the water heating in the KDC
version. The function keeps the plate heat exchanger preheated so that the period required for heating water is as
short as possible. Hold the button for 3 sec.
switching boiler
on / o
unblocking
failure
condition
mode switch
summer /
winter
comfort function
activation /
deactivation
information about
the heating water
pressure in the system
2.1.1 Boiler control panel
The controls of the boiler are located in the bottom part of the front cover of the boiler.
!
This appliance may be used by children at the age of 8 and above and by people with impaired physical, sensory
or mental abilities, or lack of experience and knowledge provided that they are supervised or that they have
been instructed on the safe use of the appliance, and that they understand the potential risks. Children must
not play with the appliance. Children must not perform cleaning and maintenance of the appliance without
supervision.

17
THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
Indication of set temperature
After turning the control knob for setting the temperature of the heating system or DHW (boilers with ow heating of DHW)
the respective symbol of the regime will start to ash along with the numeric display of the temperature on the LCD display.
In this case, the value of the last temperature set is indicated. After the termination of the setting, the indication of the set
temperature remains for about 5 seconds. The following permanent display of the numeric value and the symbol, the real
temperature of the respective regime is indicated again.
2.1.2 LCD display
Information about heating water pressure – hold the button for 1 second to display the current heating water
pressure (5 seconds)
Setting the heating temperature – rotary control knob for user setting of the output temperature of water in the
heating system within the range 30 – 80 °C. In the case of selected equitherm regulation, the shift in the heating
curve is set by the control knob (within the range ± 15 °C from the equithermal curve)
Setting the temperature of DHW – rotary knob for user setting of the requested temperature of hot water within
the range 35 - 60 °C (the recommended setting is 60 °C). Used for boilers THERM 18 KDZ 5, 25 KDZ 5, 35 KDZ 5 and
18 KDC, 25 KDC, 35 KDC, or THERM 18 KDZ, 25 KDZ and 35 KDZ for reading the temperature of DHW in the external
storage tank by NTC sensor.
Disconnection of water heating – setting the rotary control knob for user setting of the output temperature of the
hot water to the left side position (less than 10° of the route); the heating of water can be permanently disconnected
from operation.
option to disconnect the water heating
detail

18 THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
SYMBOL MEANING
Display of temperatures, failure statuses and service values
Permanent light – the boiler is in the summer or winter mode
Flashing – water is being heated, or the required water temperature needs to be set
Permanent light – boiler is in winter mode
Flashing – heating mode is active, or the required heating temperature needs to be set
Permanent light – ame detection – the burner is working
Permanent light – detected boiler failure
Permanent light – Comfort function deactivated
Flashing – Comfort function activated
Permanent light - Opentherm+ communication is active
Displayed together with the current value of the water pressure in the heating system
Description of symbols shown on the display
2.1.3 Custom menu
There are three submenus available within the user menu:
Information menu „In“ (SW version, temperature, pressure etc.)
Statistical menu „Co“ (operating data counters)
Failure register „Al“.
User menu activation
To enter the user menu (and also the information submenu), press and hold the Reset button for 5 – 10 seconds. The
display shows alternating “In” (1 sec), “00” (1 sec) indicating the order of the parameter and the value of the parameter (5
sec). The information submenu is always displayed rst when the user menu is accessed.
Browsing the menu
Browsing the menu is possible by briey pressing the On / O button. The browsing method in the menu is cyclical. When
the last item is accessed and the On / O button pressed again, the menu goes back to the rst item.
Switching between submenus
Press the Reset button shortly. Keep pressing to browse through the individual submenus (In - Co - Al).
Closing the user menu
The same as opening the user menu – hold the Reset button for 5 – 10 seconds.

19
THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
Order Description Unit
Information menu „In“
In0 SW automatics version
In1 Outside temperature °C
In2 Temperature of heating water °C
In3 Flue gas temperature °C
In4 DHW temperature °C
In5 Temperature of return water °C
In6 The required heating temperature °C
In7 Boiler output %
In8 Inactivited -
In9 Pressure of heating water bar
In10 Fan speed rpm x 100
Statistic menu „Co“
Co0 * Time of boiler connection to the power supply h x 100
Co1 * Time of burner operation h x 100
Co2 * Number of burner ignitions x 1000
Co3 Total number of detected boiler failures
Co4 Number of service menu entries
Co5 Number of OEM menu entries
Co6 Inactivited -
* If the displayed value ashes quickly, it is adecimal number.
E.g. ashing value 20 = 2.0 * 100 (or * 1000)
Failure register „Al“.
Al0 Displaying the last detected failure -
Al1 - Al9 Displaying previous failures -
List of displayed parameters

20 THERM 18 KD, KDZ, KDC, KDZ 5; 25 KD, KDZ, KDC, KDZ 5; 35 KD, KDZ, KDC, KDZ 5
rE - The boiler is blocked. To reactivate the boiler, manually reset of boiler.
The error code is saved into the memory of the processor where it is also saved in the case of asupply failure.
2.1.4 Error messages
Any potential failure or other anomaly is indicated by alternating flashing of the failure code with the text E or rE and
illumination of the LCD display.
Error code displayed on LCD and the meaning:
ERROR CODE MEANING
E 02 Low pressure of heating water
E 03 High pressure of heating water
E 04 Defect to the thermal DHW probe - KDC version
E 05 Defect to the thermal heating probe
rE 06 Blocking of the activity when the burner is not ignited
rE 07 Blocking of activity after overheating of the boiler (emergency thermostat)
rE 08 Indication of false ame
E 09 Low ow of heating water
E 10 Defect to the outside temperature sensor
E 11 Disconnected or damaged gas valve modulator
E 12 Defect to the thermal DHW probe - KDZ version
E 13 High temperature of burnt gases
E 14 Defect of the thermal probe of burnt gases
E 15 Fan control failure
E 16 Defect of the thermal probe of return water
rE 28 Recurring system blocking
E 37 Low voltage in the network
E 40 Network frequency outside the range
rE 41 Recurring loss of ame (more than 6 trials)
E 42 Control panel button defect
E 43 OpenTherm communication error
rE 44 Gas valve defect
E 62 Boiler calibration required
rE 72 Unspecied failure
E 77 System unable to regulate combustion
E 78 System unable to regulate combustion (possible low fan pressure)
E 79 System unable to regulate combustion
E 84 Possible low inlet gas pressure
rE 88 Gas valve control defect
E 89 Flame signal oscillation failure
E 90 Combustion quality out of bound or not steady
E 93 Combustion quality out of bound or not steady
E 94 Combustion quality out of bound or not steady
E 95 Flame signal is interrupted for ashort time
E 96 Exhaust or air intake blocked
rE 98 Controlling automatics SW error
rE 99 Common error